Chapter 10 - Nature of the Gene and Genome (Spring 2011)

Sequenced in 2004 the finished version of the human

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Unformatted text preview: ion of the human genome was reported contains 20000 genes, alternate splicing of mRNA may account for several proteins from one gene, post-translational modifications also account for different protein functions Comparative genomics: If it is conserved, it must be important DNA that is similar among related organisms is considered to be important even when the precise role is still unclear; some important DNA in humans may have recent origin (the chimpanzee is the closest to us) The genetic basis of being a human: by focusing on conserved sequence, we can learn about traits we share with other species The gene FOXP2 in human differs very little from that in chimps, and is called the speech gene it became fixed in the human population about 120000 to 200000 years ago The gene AMY1 encodes the enzyme amylase and its frequency is remarkably different n humans and chimps (used for starch digestion) chimps have a lower starch diet compared to humans Human Genetic Variation o o o o o The genome varies among different individuals due to genetic polymorphism DNA sequence variation the most common variability among humans is at the single nucleotide difference, called single nucleotide polymorphisms (SNPs) Segments of the genome can change and these changes may involve large segments of DNA (structural variants) Recent studies indicate that intermediate sized variants are more common than previously thought Variants: gene duplication, deletion, inversion, insertion Genomic Analysis in Medicine o o o o o Until recently, the gene responsible for a disease was indentified through traditional genetic linkage studies However the low penetrance of most genes for common diseases cannot be indentified thorough family linkage studies Genome wide association studies look for links between a disease and polymorphisms located in the genome SNPs may play an important role as susceptibility to disease or act as genetic markers for susceptibility SNPs can be inherited in blocks called haplotypes haplotype maps (Hapmaps) are based on common haplotypes and they may lead to association between disease and haplotypes 5...
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This document was uploaded on 04/10/2014.

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